NtdllPipe Like Activity Execution

Status: test
Severity: high
Log source: category process_creation, product windows
Author: Florian Roth (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects command that type the content of ntdll.dll to a different file or a pipe in order to evade AV / EDR detection. As seen being used in the POC NtdllPipe

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	No specific technique

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation
Security-Auditing	Event ID 4688: A new process has been created.

Rule body

title: NtdllPipe Like Activity Execution
id: bbc865e4-7fcd-45a6-8ff1-95ced28ec5b2
status: test
description: Detects command that type the content of ntdll.dll to a different file or a pipe in order to evade AV / EDR detection. As seen being used in the POC NtdllPipe
references:
    - https://web.archive.org/web/20220306121156/https://www.x86matthew.com/view_post?id=ntdll_pipe
author: Florian Roth (Nextron Systems)
date: 2022-03-05
modified: 2023-03-07
tags:
    - attack.defense-impairment
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains:
            - 'type %windir%\system32\ntdll.dll'
            - 'type %systemroot%\system32\ntdll.dll'
            - 'type c:\windows\system32\ntdll.dll'
            - '\\ntdll.dll > \\\\.\\pipe\\'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    CommandLine|contains:
        - 'type %windir%\system32\ntdll.dll'
        - 'type %systemroot%\system32\ntdll.dll'
        - 'type c:\windows\system32\ntdll.dll'
        - '\\ntdll.dll > \\\\.\\pipe\\'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`\\ntdll.dll > \\\\.\\pipe\\` `type %systemroot%\system32\ntdll.dll` `type %windir%\system32\ntdll.dll` `type c:\windows\system32\ntdll.dll`	`field:"CommandLine" kind:match`